Dipole Meter


Theory: Dipole Meter is an adaptable instrument that is used for measuring the dielectric constant of non-polar liquids. In the equipments a particular circuit has been developed for audio oscillator that produces stabilized wave. In this experiment dielectric cell is standardized using reference liquid having known dielectric constant by immersing the dielectric cell assembly in to reference Liquid. Then experimental liquid whose dielectric constant has to be determined is taken and assembly is immersed into liquid, resulting in change in oscillation frequency. From resulting shift, capacitance of cell in unknown liquid is calculated (CX). Dielectric Constant of unknown liquid is calculated using relation:

Where Capacitance of Air,Capacitance of standard liquid, Capacitance of test liquid and dielectric constant of standard liquid solution of polar molecule having molecular wt. with non-polar solvent having molecular wt. in different concentrations, is considered. Molar Polarization of the mixture is obtained by relation

Where k is dielectric constant of the solution having mole fraction of polar molecule and mole fraction of non polar solvent and is the density of the mixture.

A graph between and is obtained The dipole moment is calculated using relation, Where T is absolute temperature, is molar polarization of non-polar liquid and is molar polarisation of non polar liquid.

Specifications:

Main Unit having Frequency Counter, Audio Oscillator and suitable Electronic Circuity Dielectric Cell Unit consists of
1 .Dielectric Cell (SS) assembly with Teflon top & BNC connector
2. Beaker (100 ml)
3. Attachment for circulation of water from external water bath